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Question about the wind analysis

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deepyaman.chakraborty2018
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Question about the wind analysis

 

Hello,

 

I had a few questions, again:😁

 

The Lawson LDDC is based on the London guidelines, so are you using a fixed threshold velocity for sitting, standing, and other states?

Or are you calculating something based on the current stock of buildings(imported)?

 

As referred to in the table on the left-hand side of this document - https://www.cityoflondon.gov.uk/assets/Services-Environment/wind-microclimate-guidelines.pdf - page 9. - The mean velocities are fixed and native to certain places in London only.

 

Does that mean I should not use lawson-lddc from spacemaker if my area is elsewhere?

 

Thank you.


@deepyaman.chakraborty2018 Adjusted the title of this topic as I moved the topic from a different thread.

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Message 2 of 3


@deepyaman.chakraborty2018 wrote:

 

Hello,

 

I had a few questions, again:😁

 

The Lawson LDDC is based on the London guidelines, so are you using a fixed threshold velocity for sitting, standing, and other states?

Or are you calculating something based on the current stock of buildings(imported)?

 

As referred to in the table on the left-hand side of this document - https://www.cityoflondon.gov.uk/assets/Services-Environment/wind-microclimate-guidelines.pdf - page 9. - The mean velocities are fixed and native to certain places in London only.

 

Does that mean I should not use lawson-lddc from spacemaker if my area is elsewhere?

 

Thank you.


Hello again,

 

There are a few different factors in your question which it is important to separate. First of all, although we think the City of London has done a great job creating these guidelines for urban wind analysis, we do not strive to do things exactly as described there -- but we do take the arguments they present and choices they've made into consideration when developing the wind analysis in Spacemaker. 

 

With reference to your questions: 

  • Yes, we use fixed thresholds for each of the pedestrian comfort categories. You can see exactly what they are here. 
  • Imported buildings are analyzed in order to make sure we include relevant geometries and make the CFD wind tunnel large enough to their effect on the ground results. But they do not have any effect on pedestrian comfort thresholds. And we're not aware of any pedestrian comfort computation where this is done. 
  • Looking at the document which you linked, it is not the pedestrian comfort thresholds but the statistical properties of wind climate - i.e. the Weibull distributions describing the probability of wind at a certain speed from each direction (read more here). We fetch this data from e.g. Global Wind Atlas, and it is equally valid in London and at other locations (more info). 

So no, whether or not your location is based in London does not decide whether the Lawson LDDC scale is applicable. But if you are interested in which comfort scale to choose, there are as many opinions on this as there are proposed comfort scales (try googling "which pedestrian comfort scale" and you'll find a few discussions). There may be specific regulations in your area, so it could be a good idea to have a chat with your favourite local wind specialist. Maybe invite them to check out the project together in Spacemaker? 😉

 

Hope that clarifies things - thanks again for showing an interest and asking questions! 

Message 3 of 3

Thanks again!!

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